Distinguishing between buried semiconductor/metal contacts and hybrid semiconductor/metal/liquid contacts at n-GaAs/KOH-Se-/2-(aq) junctions

Ashish Bansal, Ming X. Tan, Bruce J. Tufts, Nathan S Lewis

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The current-voltage properties of n-GaAs photoanodes have been evaluated in KOH-Se-/2-(aq), CH3CN-Fc+/0, and CH3CN-MV2+/+ solutions. Chemisorption of transition-metal ions (RhIII, CoIII, RuIII, OsIII) onto n-GaAs has been shown previously to effect improved photoanode behavior for n-GaAs/KOH-Se-/2-(aq) contacts, but it is not clear whether the chemisorbed metal forms a buried semiconductor/metal junction or results in a hybrid semiconductor/metal/liquid contact. After chemisorption of transition-metal ions, n-GaAs photoanodes displayed different open circuit voltages in contact with each electrolyte solution investigated. The role of the chemisorbed metal in the n-GaAs/M/KOH-Se-/2-(aq) system is, therefore, best described as catalyzing interfacial charge transfer at the semiconductor/liquid interface, as opposed to establishing a semiconductor/metal or semiconductor/ insulator/metal contact that is exposed to, but not influenced by, the electrolyte solution.

Original languageEnglish
Pages (from-to)7309-7315
Number of pages7
JournalJournal of Physical Chemistry
Issue number28
Publication statusPublished - 1993


ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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